State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan University, Haikou, China.
Hainan Provincial Key Laboratory for Tropical Hydrobiology and Biotechnology, College of Marine Science, Hainan University, Haikou, China.
Front Immunol. 2021 Jan 18;11:617522. doi: 10.3389/fimmu.2020.617522. eCollection 2020.
R848 is an imidazoquinoline compound that is a specific activator of toll-like receptor (TLR) 7/8 and is often used in immunological research in mammals and teleosts. However, the immune responses initiated by R848 through the TLR7/8 pathway in response to bacterial infection remain largely unexplored in teleosts. In the current study, we investigated the antibacterial response and the participating signaling pathway initiated by R848 in golden pompano (). We found that R848 could stimulate the proliferation of head kidney lymphocytes (HKLs) in a dose-dependent manner, enhance the survival rate of HKLs, and inhibit the replication of bacteria . However, these effects induced by R848 were significantly reduced when chloroquine (CQ) was used to blocked endosomal acidification. Additionally, an study showed that R848 strengthened the antibacterial immunity of fish through a TLR7/8 and Myd88-dependent signaling pathway. A cellular experiment showed that Pepinh-MYD (a Myd88 inhibitor) significantly reduced the R848mediated proliferation and survival of HKLs. Luciferase activity analysis showed that R848 enhanced the nuclear factor kappa B (NF-κB) activity, whereas this activity was reduced when CQ and Pepinh-MYD were present. Additionally, when an NF-κB inhibitor was present, the R848-mediated pro-proliferative and pro-survival effects on HKLs were significantly diminished. An study showed that knockdown of TLR7, TLR8, and Myd88 expression in golden pompano siRNA following injection of R848 resulted in increased bacterial dissemination and colonization in fish tissues compared to that of fish injection of R848 alone, suggesting that R848-induced antibacterial immunity was significantly reduced. In conclusion, these results indicate that R848 plays an essential role in the antibacterial immunity of golden pompano the TLR7/8-Myd88-NF-κB- signaling pathway.
R848 是一种咪唑并喹啉化合物，是 Toll 样受体 (TLR) 7/8 的特异性激活剂，常用于哺乳动物和硬骨鱼的免疫学研究。然而，R848 通过 TLR7/8 途径在硬骨鱼中对细菌感染引发的免疫反应在很大程度上仍未得到探索。在本研究中，我们研究了 R848 在金鲳鱼（）中引发的抗细菌反应和参与的信号通路。我们发现，R848 可以剂量依赖性地刺激头肾淋巴细胞（HKL）的增殖，提高 HKL 的存活率，并抑制细菌的复制。然而，当使用氯喹（CQ）阻断内体酸化时，R848 诱导的这些效应显著降低。此外，一项研究表明，R848 通过 TLR7/8 和 Myd88 依赖的信号通路增强了鱼类的抗菌免疫。一项细胞实验表明，Pepinh-MYD（一种 Myd88 抑制剂）显著降低了 R848 介导的 HKL 增殖和存活。荧光素酶活性分析表明，R848 增强了核因子 kappa B（NF-κB）的活性，而当存在 CQ 和 Pepinh-MYD 时，该活性降低。此外，当存在 NF-κB 抑制剂时，R848 对 HKL 介导的促增殖和促存活作用显著减弱。一项研究表明，在注射 R848 后，金鲳鱼中 TLR7、TLR8 和 Myd88 表达的 knockdown 导致与单独注射 R848 的鱼相比，鱼组织中的细菌传播和定植增加，表明 R848 诱导的抗菌免疫显著降低。总之，这些结果表明，R848 在金鲳鱼的抗菌免疫中发挥重要作用，该作用是通过 TLR7/8-Myd88-NF-κB-信号通路实现的。
